DESCRIPTION

These functions operate efficiently on memory areas
(arrays of bytes bounded by a count, not terminated by a zero byte).
They do not check for the overflow of any receiving memory area.

Memccpy
copies bytes from memory area
s2
into
s1,
stopping after the first occurrence of byte
c
has been copied, or after
n
bytes have been copied, whichever comes first.
It returns a pointer to the byte after
the copy of
c
in
s1,
or zero if
c
was not found in the first
n
bytes of
s2.

Memchr
returns a pointer to the first
occurrence of byte
c
in the first
n
bytes of memory area
s,
or zero if
c
does not occur.

Memcmp
compares its arguments, looking at the first
n
bytes only, and returns an integer
less than, equal to, or greater than 0,
according as
s1
is lexicographically less than, equal to, or
greater than
s2.
The comparison is bytewise unsigned.

Memcpy
copies
n
bytes from memory area
s2
to
s1.
It returns
s1.

Memmove
works like
memcpy,
except that it is guaranteed to work if
s1
and
s2
overlap.

Memset
sets the first
n
bytes in memory area
s
to the value of byte
c.
It returns
s.

SOURCE

All these routines have portable C implementations in
/sys/src/libc/port.
Most also have machine-dependent assembly language implementations in
/sys/src/libc/$objtype.